Plate Tectonics What are Plate Tectonics A theory

Plate Tectonics

What are Plate Tectonics? �A theory that Earth’s Surface is divided into a few large plates that are constantly moving and changing shape. �Geological evidence indicates that the face of Earth's surface has changed significantly since its initial formation.

What do Plate tectonics involve? �Plate tectonics involves two layers of Earth: the lithosphere and the asthenosphere �The lithosphere is divided into several major and minor tectonic plates. �The lithosphere is a rigid outer layer composed of the crust and the uppermost mantle. �The asthenosphere is an inner layer about 200 kilometers thick located exclusively in the mantle.

Fun Facts about Plate Tectonics �Tectonic Plates move extremely slow, at a rate of 12 centimeters per year. �Heat from Earth’s interior provides the energy necessary to move plates. �Earth is the only planet known to have plate tectonics. �In 200 million years the world will look much different then it does today. This is because some of our present day continents maybe spilt apart and be separated by new oceans.

Pangaea A supercontinent that broke apart 200 million years ago to form the present continents.

Plate Names The plate names are: North American Plate, Juan de Fuca Plate, Pacific Plate, Caribbean Plate, Cocos Plate, Nazca Plate, South American Plate, Scotia Plate, African Plate, Antarctic Plate, Arabian Plate, Indian Plate, Eurasian Plate, Australian Plate, Philippine Plate.

What are the Results of Plate Tectonics? �Volcanoes �Earthquakes �Faulting

Volcanoes occur along the earth's tectonic plates where molten rock is forced upward from magma reservoirs deep in the earth. A volcano is a mountain formed of lava and/or tephra.

A Map of Volcanoes Around the World

Earthquakes An earthquake happens when two plates rub together. The plates travel in different directions and also at different speeds. If one plate is forced underneath the other, pressure builds up until the plates rip apart. This process causes the ground to move which is known as an earthquake.

A Map of Earthquakes Around the World

Faulting A fault is a crack in the Earth’s crust. Faults are typically associated with/form the boundaries between Earth’s tectonic plates.

Types of Plate Boundaries • Transform • Divergent • Convergent

Divergent �Occur where plate motions cause plates to move apart. �For example, South America and Africa are on either side of the Mid-Atlantic Ridge, a divergent plate boundary. �Divergent plate boundaries form a wide, steep-walled depression also know as a rift valley.

Convergent �At a convergent boundary, plates move toward each other. �Mountains are formed from convergent plate boundaries.

Transform A Transform Boundary occurs where two plates slide past each other. Examples of Transform Boundaries are: • The boundary between the Pacific Plate and the Australian Plate, crossing New Zealand • The boundary between the Pacific Plate and the North American Plate in California